Why don’t people maintain infrastructure? If it is infrastructure that is nearly 100 years old, you can bet that it needs maintenance. While there were problems with the design, maintenance was definitely an issue. Lake Delhi Dam (Iowa, 2010). That is from Dam Failures, a project of the Association of State Dam Safety Officials.
Later in the week we have an anniversary of a dam failure.
Built in the 1920s for hydroelectric power, the Delhi Dam was 60 feet long, not including the powerhouse and the spillway, and 59 feet high.
The dam, which had maintained successful operations for over 90 years prior to the failure, was inspected by an Iowa Department of Natural Resources dam safety representative every five years. During the 2009 inspection, repairs to one of the three spillway gates, which was inoperable at the time, were advised. The Lake Delhi Recreation Association (LDRA), which owned and operated the dam, agreed to complete the repairs by the end of the calendar year.
That is they were to have been completed by the end of 2009. They had been started in 2010, but were not complete.
You should not have to be told to repair the spillway gate on dam if it doesn’t work. As for the design, the total available spillway volume was not sufficient to drain the reservoir, and with about 1/3 of the spillway not available, due to the non-functioning gate, disaster only required a massive storm.
Record rainfall and flooding impacted the state of Iowa during July of 2010. As a result, the area draining to Lake Delhi Dam received approximately 10 inches of rain over the course of 12 hours. This caused overtopping of the dam and its eventual failure on July 24, 2010.
The hazardous nature of the dam was never ironed out in the 90 some odd years it stood, so there was no disaster plan in place. Still, loss of life was averted. Here’s a link to a photo taken during the breach from one side of the dam.
The complete report on the incident can be found at this link. It includes a lot of info, including the image linked above and several more. And one disturbing note on inspections.
Dam inspectors performing inspections for the DNR and consulting engineering firms performing dam safety evaluations should have strong backgrounds in dam engineering and potential failure modes analysis. There were design weaknesses at Delhi Dam that an experienced dam engineer should have recognized, which likely would have led to additional investigations.
That people doing dam inspections don’t have “strong backgrounds in dam engineering” is a problem, to my way of thinking. So who is inspecting the dams? The governor’s second cousin?
If you look through my posts tagged with “Infrastructure,” the dam failures are almost always about maintenance problems, even when the inspection reports gave the dams in question a clean bill of health. “The dam has been fine for 90 years! What could go wrong?”
After the break there is video of the remains of the dam from one day after the breach, while the lake is still draining. There are quite a few videos at the link at the top of this post. Click thru, and look for the “Videos” tab.
The dam was reconstructed and the lake “reopened” in 2016.
A video by Christopher Gannon: Lake Delhi: A Lake and Dam, Gone